Avoid UB for deep nested processes

Also increase the limit for nesting by using 64 bit integers.

ProcessList.c:242:36: runtime error: left shift of 1 by 31 places cannot be represented in type 'int'
    #0 0x561cfec000a8 in ProcessList_buildTreeBranch ProcessList.c:242:36
    #1 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #2 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #3 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #4 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #5 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #6 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #7 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #8 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #9 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #10 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #11 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #12 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #13 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #14 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #15 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #16 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #17 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #18 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #19 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #20 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #21 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #22 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #23 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #24 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #25 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #26 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #27 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #28 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #29 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #30 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #31 0x561cfebffec2 in ProcessList_buildTreeBranch ProcessList.c:243:7
    #32 0x561cfebfb734 in ProcessList_buildTree ProcessList.c:312:10
    #33 0x561cfebfb050 in ProcessList_updateDisplayList ProcessList.c:326:10
    #34 0x561cfebfc58b in ProcessList_rebuildPanel ProcessList.c:374:4
    #35 0x561cfec07953 in checkRecalculation ScreenManager.c:139:7
    #36 0x561cfec07953 in ScreenManager_run ScreenManager.c:226:10
    #37 0x561cfeb8899a in CommandLine_run CommandLine.c:378:4
    #38 0x561cfeb6d6d4 in main htop.c:15:11
    #39 0x7f14860291e9 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #40 0x7f148602929b in __libc_start_main csu/../csu/libc-start.c:392:3
    #41 0x561cfeaafb20 in _start (htop+0x105b20) (BuildId: fc4b9e52ffc111ca8b4cd53136a238414120a858)

Process.c

@@ -784,9 +784,9 @@ void Process_writeField(const Process* this, RichString* str, ProcessField field
       char* buf = buffer;
       const bool lastItem = (this->indent < 0);
 
-      for (int indent = (this->indent < 0 ? -this->indent : this->indent); indent > 1; indent >>= 1) {
+      for (uint32_t indent = (this->indent < 0 ? -this->indent : this->indent); indent > 1; indent >>= 1) {
          int written, ret;
-         if (indent & 1) {
+         if (indent & 1U) {
             ret = xSnprintf(buf, n, "%s  ", CRT_treeStr[TREE_STR_VERT]);
          } else {
             ret = xSnprintf(buf, n, "   ");

Process.h

@@ -242,7 +242,7 @@ typedef struct Process_ {
    /*
     * Internal state for tree-mode.
     */
-   int indent;
+   int32_t indent;
    unsigned int tree_depth;
 
    /* Has no known parent process */

ProcessList.c

@@ -199,7 +199,7 @@ static void ProcessList_removeIndex(ProcessList* this, const Process* p, int idx
    assert(Vector_countEquals(this->processes, Hashtable_count(this->processTable)));
 }
 
-static void ProcessList_buildTreeBranch(ProcessList* this, pid_t pid, int level, int indent, bool show) {
+static void ProcessList_buildTreeBranch(ProcessList* this, pid_t pid, unsigned int level, int32_t indent, bool show) {
    // On OpenBSD the kernel thread 'swapper' has pid 0.
    // Do not treat it as root of any tree.
    if (pid == 0)
@@ -239,7 +239,7 @@ static void ProcessList_buildTreeBranch(ProcessList* this, pid_t pid, int level,
 
       Vector_add(this->displayList, process);
 
-      int nextIndent = indent | (1 << level);
+      int32_t nextIndent = indent | ((int32_t)1 << MINIMUM(level, sizeof(process->indent) * 8 - 2));
       ProcessList_buildTreeBranch(this, process->pid, level + 1, (i < lastShown) ? nextIndent : indent, process->show && process->showChildren);
       if (i == lastShown) {
          process->indent = -nextIndent;